The manipulation of needles through tissue, catheters through blood vessels, and other minimally invasive devices which reach targets in the body is the initial step of nearly all MRI-guided interventions. To date, most research on MRI targeting has focused on using MRI to image the target, and to plan the trajectory of interventional devices. During the subsequent manipulation, however, it is useful to track any deviation from the planned trajectory to minimize positioning error and procedural complications. Previous techniques for tracking devices include rapid MRI, MR-tracking, and gradient-based tracking (“Endoscout®”, Robin Medical Inc). These methods are all limited because they require use of the MRI system during manipulation, require the device to be within the homogeneous volume of the gradient fields used for imaging, and because susceptibility artifacts from MRI-compatible metallic devices may cause distortions that lead to poor signal and/or inaccurate position information. The latter two tracking methods also require integration of an electronic apparatus into the interventional devices, which further increases device complexity including adding the need for appropriate patient isolation electronics.
Additionally, in the prior art, a catheter which is guided through blood vessels is not able to indicate the state of roughness of the interior lumen of the vessel, and it would be desired to provide a measure of roughness of the lumen.
In one prior art catheter, a series of cables are used to steer the catheter, such as through a bifurcation in the blood vessels.